Single-operator-exchange (SOE) or “monorail” catheters are catheters in which only a distal portion of the catheter tracks over a guidewire. Proximal of the distal portion that tracks the guidewire, the guidewire is located exterior of the catheter shaft. Therefore, the proximal portion of an SOE catheter need not include a guidewire lumen, which would be necessary in an over-the-wire (OTW) catheter construction. An SOE catheter has advantages in that, by not tracking the guidewire over its entire length, the catheter and guidewire are more easily moved relative to one another, such as during a catheter exchange during a medical procedure. One example of an early patent in this area is U.S. Pat. No. 5,156,594 to Keith, the disclosure of which is incorporated herein by reference.
One drawback of SOE catheters is the difficulty of fabrication. Construction of an SOE device typically involves securing several lengths of tubing together such that a distal portion of the SOE catheter includes an additional lumen for receiving a guidewire. A guidewire opening or port is provided to allow a guidewire to be introduced into the guidewire lumen through the guidewire port. A number of different manners of providing the guidewire port joint to a rapid exchange-type of medical device have been suggested, for example, by Fitzmaurice et al., U.S. Pat. No. 6,190,358; Enger, U.S. Pat. No. 5,980,486; Estrada et al., U.S. Pat. No. 6,193,686; and Williams et al., U.S. Pat. No. 6,409,863. U.S. Pat. No. 6,409,863 to Williams is incorporated herein by reference. The disclosure of the Keith patent above, incorporated by reference, discloses a crimped hypotube, which is then adhesively attached to a distal polymer member having a guidewire tube and an outer tube around the guidewire tube.
Another drawback of SOE catheters is the integrity and kink resistance of the elongate shaft proximate the guidewire port joints, as well as the pushability of the various portions of the shaft. Therefore, there is an ongoing need to provide catheter constructions which enhance the performance of the catheter by providing improved pushability and kink resistance to the catheter shaft.